There exist numerous applications in which metal articles are exposed to high temperatures. Such applications relate, for example, to a variety of aerospace applications and also to terrestrial operations where parts are used in gas turbine engines.
In all these applications, it is important to provide means for avoiding excessively fast wear of articles subjected to friction or contact in normal use, given that such wear considerably shortens their lifetime and can lead to real problems concerning performance and safety.
Articles of this type, such as rolling parts or cams, usually present a contact surface that is not plane and that may be more or less irregular in shape.
Conventionally, such articles are coated, in particular on their contact surfaces, with a coating that improves their ability to withstand wear at high temperatures.
Usually, the coatings are deposited by various techniques such as vapor deposition, plasma sputtering, electrolysis, chemical means, etc.
Given that the contact surface for coating may present a shape that is very complex, it is difficult to obtain uniform thicknesses by using those direct deposition techniques. In addition, the cost and the limitations of those deposition techniques do not enable large thickness to be obtained for such protective coatings.